JP2024068133A - CMP slurry composition for tungsten polishing and method for polishing tungsten using the same - Google Patents

Abstract

To provide a CMP slurry composition for tungsten polishing, which has a high polishing rate and low erosion, thereby improving flatness after polishing.SOLUTION: A CMP slurry composition for tungsten polishing includes one or more of polar and non-polar solvents, an abrasive, and a compound of chemical formula 3 or a complex compound thereof.SELECTED DRAWING: None

Description

The present invention relates to a CMP slurry composition for tungsten polishing and a method for polishing tungsten using the same.

Chemical mechanical polishing (CMP) compositions and methods for polishing (or planarizing) the surface of a substrate are widely known in the relevant art.

The process of polishing a metal layer using a CMP composition includes a step of polishing only the initial metal layer, a step of polishing the metal layer and barrier layer, and a step of polishing the metal layer, barrier layer, and oxide film. Among these steps, a tungsten pattern wafer polishing composition is used in the step of polishing the metal layer, barrier layer, and oxide film, and excellent polishing planarization can be achieved when the metal layer and oxide film are polished at an appropriate polishing rate.

A polishing composition for polishing a metal layer (e.g., tungsten) on a semiconductor substrate can include abrasive particles suspended in an aqueous solution and a chemical promoter, such as an oxidizer or catalyst. Among these, the catalyst serves to increase the polishing rate of tungsten, and several types of catalysts are known to be usable in the CMP field. However, some catalysts can increase the polishing rate, but can also deteriorate the flatness after polishing.

The object of the present invention is to provide a CMP slurry composition for tungsten polishing that has a high polishing rate and low erosion, thereby improving the flatness after polishing.

1. According to one embodiment, the CMP slurry composition for tungsten polishing includes at least one solvent selected from polar and non-polar solvents; an abrasive; and a compound of the following formula 3 or a complex thereof:

(In the above Chemical Formula 3,
R ¹ , R ² , and R ³ each independently represent a single bond or a substituted or unsubstituted alkylene group having 1 to 3 carbon atoms;
R ⁴ , R ⁵ , and R ⁶ each independently represent a substituted or unsubstituted alkylene group having 1 to 3 carbon atoms;
M ¹ , M ² and M ³ are each independently OH or O ⁻ M ⁺ (M ⁺ is a monovalent cation).

In 2.1, the compound of formula 3 may be a compound of formula 3-1 below or a salt thereof with an alkali metal cation:

.

In 3.1-2, the complex compound may be a compound of formula 3 that is coordinate-bonded to a metal ion.

In 4.1-3, the metal ion may be a divalent iron cation (Fe ²⁺ ) or a trivalent iron cation (Fe ³⁺ ).

In 5.1-4, the complex compound may be a complex compound represented by the following chemical formula 4:

.

In 6.1-5, the compound of Chemical Formula 3 or its complex compound may be included in the CMP slurry composition in an amount of 0.001 wt % to 10 wt %.

In 7.1-6, the abrasive may include one or more of an unmodified abrasive and a modified abrasive.

In 8.7, the modified abrasive may include silica modified with an aminosilane having 1 to 5 nitrogen atoms.

9. In 1-8, the composition may further include one or more of an oxidizing agent, an amino acid, and an organic acid.

In 10.9, the composition may include 0.001% to 20% by weight of the abrasive, 0.001% to 10% by weight of the compound of formula 3 or its complex compound, 0.001% to 10% by weight of the organic acid, 0.001% to 10% by weight of the amino acid, and 30% to 99% by weight of the solvent.

In 11.1-10, the CMP slurry composition may have a pH of 2 to 7.

12. According to one embodiment, the tungsten polishing method includes polishing tungsten using the CMP slurry composition for tungsten polishing.

The present invention provides a CMP slurry composition for tungsten polishing that has a high polishing rate and low erosion, improving the flatness after polishing.

The terms used herein are merely used to describe each illustrative embodiment and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In this specification, "substituted" in "substituted or unsubstituted" means that one or more hydrogen atoms of the functional group in question are substituted with any one of a hydroxyl group, an alkyl group or a haloalkyl group having 1 to 20 carbon atoms, an alkenyl group or a haloalkenyl group having 2 to 20 carbon atoms, an alkynyl group or a haloalkynyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a cycloalkenyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an arylalkyl group having 7 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, an amino group, a halo group, a cyano group, and a thiol group.

In this specification, a "monovalent aliphatic hydrocarbon group" may be a substituted or unsubstituted linear or branched alkyl group having 1 to 20 carbon atoms, preferably an alkyl group having 1 to 10 carbon atoms, and more preferably an alkyl group having 1 to 5 carbon atoms.

In this specification, the "monovalent alicyclic hydrocarbon group" may be a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, preferably a cycloalkyl group having 3 to 10 carbon atoms, and more preferably a cycloalkyl group having 3 to 5 carbon atoms.

In this specification, the "monovalent aromatic hydrocarbon group" may be a substituted or unsubstituted aryl group having 6 to 20 carbon atoms or a substituted or unsubstituted arylalkyl group having 7 to 20 carbon atoms, preferably an aryl group having 6 to 10 carbon atoms or an arylalkyl group having 7 to 10 carbon atoms.

In this specification, the terms "divalent aliphatic hydrocarbon group", "divalent alicyclic hydrocarbon group" and "divalent aromatic hydrocarbon group" refer to the above-mentioned "monovalent aliphatic hydrocarbon group", "monovalent alicyclic hydrocarbon group" and "monovalent aromatic hydrocarbon group" each modified to a divalent form.

For example, the "divalent aliphatic hydrocarbon group" may be a substituted or unsubstituted linear or branched alkylene group having 1 to 20 carbon atoms, preferably an alkylene group having 1 to 10 carbon atoms, more preferably an alkylene group having 1 to 5 carbon atoms; the "divalent alicyclic hydrocarbon group" may be a substituted or unsubstituted cycloalkylene group having 3 to 20 carbon atoms, preferably a cycloalkylene group having 3 to 10 carbon atoms, more preferably a cycloalkylene group having 3 to 5 carbon atoms; the "divalent aromatic hydrocarbon group" may be a substituted or unsubstituted arylene group having 6 to 20 carbon atoms or a substituted or unsubstituted arylalkylene group having 7 to 20 carbon atoms, preferably an arylene group having 6 to 10 carbon atoms or an arylalkylene group having 7 to 10 carbon atoms.

In this specification, when describing a numerical range, "X to Y" means greater than or equal to X and less than or equal to Y.

The present invention relates to a CMP slurry composition for tungsten polishing. The composition not only has a high polishing rate, but also has low erosion, etc., and therefore provides the effect of improving the flatness after polishing. In particular, the CMP slurry composition for tungsten polishing of the present invention is used for polishing tungsten pattern wafers, and can provide the effect of improving the flatness after polishing, since it has a high polishing rate for oxide films and low erosion, etc.

The CMP slurry composition for tungsten polishing of the present invention (hereinafter referred to as "CMP slurry composition") contains one or more solvents selected from polar and non-polar solvents; an abrasive; and a compound of the following chemical formula 3 or a complex compound thereof.

solvent

At least one of the polar solvent and the nonpolar solvent can reduce friction when tungsten or a tungsten pattern wafer is polished with an abrasive. At least one of the polar solvent and the nonpolar solvent may be water (e.g., ultrapure water or deionized water), an organic amine, an organic alcohol, an organic alcohol amine, an organic ether, an organic ketone, or the like. Preferably, the solvent may include ultrapure water or deionized water. At least one of the polar solvent and the nonpolar solvent may be included in the remaining amount, for example, 30% to 99% by weight, of the CMP slurry composition.

Abrasive

The abrasive can polish insulating layers (e.g. silicon oxide) and tungsten pattern wafers at high polishing rates.

The abrasive may include one or more of silica, including colloidal silica, fumed silica, and metal oxides such as ceria and alumina. Preferably, the abrasive may include colloidal silica, fumed silica, and more preferably colloidal silica.

The abrasive may be spherical or non-spherical particles, and the average particle size (D50) of the primary particles may be 10 nm to 200 nm, specifically 20 nm to 180 nm, and more specifically 30 nm to 150 nm. This range can increase the polishing speed of the insulating layer film and tungsten pattern wafer, which are the polishing targets of the present invention. The "average particle size (D50)" refers to a normal particle size known to those skilled in the art, and refers to the particle size of the particles that make up 50% by volume when the abrasive is distributed in order from smallest to largest based on volume.

The abrasive may include one or more of an unmodified abrasive and a modified abrasive. Preferably, the composition includes a modified abrasive, which can improve the polishing rate of the insulating layer film and reduce scratches compared to unmodified abrasives, and can achieve a high polishing rate of the tungsten pattern wafer even in a weakly acidic pH range that is higher than conventional strong acidity.

In one embodiment, the modified abrasive is modified with silane alone, which has one or more nitrogen atoms, and has a positive charge on the surface of the abrasive. Specifically, the modified abrasive can have a surface zeta potential of +10 mV to +100 mV, specifically +20 mV to +60 mV. This range can help improve the polishing rate of the insulating layer film.

In one specific example, the modified abrasive can be prepared by adding an aminosilane having one or more nitrogen atoms to an unmodified abrasive in a molar ratio of 0.02 to 1 relative to the unmodified abrasive under acidic conditions, followed by stirring at 50°C to 80°C for 10 to 30 hours. The acidic conditions can be achieved by adding an acid such as hydrochloric acid, hydrofluoric acid, acetic acid, nitric acid, or sulfuric acid. The unmodified abrasive can be, but is not limited to, colloidal silica, fumed silica, or more preferably colloidal silica.

In one embodiment, the abrasive may be modified with an aminosilane having one or more nitrogen atoms, for example, from one to five. Preferably, the abrasive may be modified with one or more of the aminosilanes having two nitrogen atoms and the aminosilanes having three nitrogen atoms, described below.

Silane with two nitrogen atoms

The silane having two nitrogen atoms may include a compound of formula 1, a cation derived from a compound of formula 1, or a salt of a compound of formula 1:

(In the above Chemical Formula 1,
X ₁ , X ₂ and X ₃ each independently represent a hydrogen atom, a hydroxyl group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryloxy group having 6 to 20 carbon atoms;
At least one of X ₁ , X ₂ , and X ₃ is a hydroxyl group, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryloxy group having 6 to 20 carbon atoms;
Y ₁ and Y ₂ each independently represent a single bond, a divalent aliphatic hydrocarbon group, a divalent alicyclic hydrocarbon group, or a divalent aromatic hydrocarbon group;
R ₁ , R ₂ , and R ₃ are each independently a hydrogen atom, a hydroxyl group, a substituted or unsubstituted monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

In one embodiment, the abrasive may include an abrasive modified with the compound of formula 1.

Preferably, in Formula 1, _X1 , _X2 , and _X3 are each independently a hydroxyl group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, and at least one of _X1 , _X2 , and _X3 is a hydroxyl group, or a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms. More preferably, in Formula ₁ , X1, _X2 , and _X3 are a hydroxyl group, or a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms. Through this, the compound of Formula 1 is more stably bound to the abrasive, thereby extending the life of the abrasive.

Preferably, Y ₁ and Y ₂ are each independently a divalent aliphatic hydrocarbon group, more preferably an alkylene group having 1 to 5 carbon atoms.

Preferably, in Formula 1, R ₁ , R ₂ and R ₃ are each independently hydrogen, and Formula 1 may be an amino group (—NH ₂ )-containing silane.

For example, the compound of Chemical Formula 1 may include one or more of aminoethylaminopropyltrimethoxysilane, aminoethylaminopropyltriethoxysilane, aminoethylaminopropylmethyldimethoxysilane, aminoethylaminopropylmethyldiethoxysilane, aminoethylaminomethyltriethoxysilane, and aminoethylaminomethylmethyldiethoxysilane.

In other embodiments, the abrasive may include an abrasive modified with a cation derived from the compound of Formula 1.

The cation derived from the compound of Chemical Formula 1 refers to a cation formed by further bonding hydrogen or a substituent to one or more of the two nitrogens in Chemical Formula 1. The cation may be a monovalent cation or a divalent cation. For example, the cation may be represented by any one of the following Chemical Formulas 1-1 to 1-3:

(In the formulas 1-1 to 1-3, X ₁ , X ₂ , X ₃ , Y ₁ , Y ₂ , R ₁ , R ₂ , and R ₃ are each as defined in the formula 1,
R ₄ and R ₅ are each independently a hydrogen atom, a hydroxyl group, a substituted or unsubstituted monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

In yet another embodiment, the polishing agent may include a polishing agent modified with a salt of the compound of Chemical Formula 1. The salt of the compound of Chemical Formula 1 refers to a neutral salt of a cation and anion derived from the compound of Chemical Formula 1 described above.

The cation may be represented by any one of the above-mentioned formulas 1-1 to 1-3. The anion may be a halogen anion (e.g., F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ ), an organic acid anion such as a carbonate anion (e.g., CO ₃ ²⁻ , HCO ₃ ⁻ ), a nitrate anion (CH ₃ COO ⁻ ), or a citrate anion (HOC(COO ⁻ )(CH ₂ COO ⁻ ) ₂ ), a nitrogen-containing anion (e.g., NO ₃ ⁻ , NO ₂ ⁻ ), a phosphorus-containing anion (e.g., PO ₄ ³⁻ , HPO ₄ ²⁻ , H ₂ PO ₄ ⁻ ), a sulfur-containing anion (e.g., SO ₄ ²⁻ , HSO ₄ ⁻ ), or a cyanide anion (CN ⁻ ).

Silane with three nitrogen atoms

The silane having three nitrogen atoms may include a compound of formula 2, a cation derived from a compound of formula 2, or a salt of a compound of formula 2:

(In the above Chemical Formula 2,
X ₁ , X ₂ and X ₃ are as defined in Formula 1;
Y ₃ , Y ₄ , and Y ₅ each independently represent a single bond, a divalent aliphatic hydrocarbon group, a divalent alicyclic hydrocarbon group, or a divalent aromatic hydrocarbon group;
R ₆ , R ₇ , R ₈ and R ₉ are each independently a hydrogen atom, a hydroxyl group, a substituted or unsubstituted monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

In one embodiment, the abrasive may include an abrasive modified with the compound of formula 2.

Preferably, in Formula 2, _X1 , _X2 , and _X3 are each independently a hydroxyl group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, and at least one of _X1 , _X2 , and _X3 is a hydroxyl group, or a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms. More preferably, in Formula 2, _X1 , _X2 , and _X3 are a hydroxyl group, or a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms. Through this, the compound of Formula 2 is more stably bonded to silica, thereby extending the life of the abrasive.

Preferably, in the above formula 2, Y ₃ , Y ₄ and Y ₅ may each independently be a divalent aliphatic hydrocarbon group, more preferably an alkylene group having 1 to 5 carbon atoms.

Preferably, in Formula 2, R ₆ , R ₇ , R ₈ and R ₉ are each independently hydrogen, and Formula 2 may be an amino group (—NH ₂ )-containing silane.

For example, the compound of formula 2 may include one or more of diethylenetriaminopropyltrimethoxysilane, diethylenetriaminopropyltriethoxysilane, diethylenetriaminopropylmethyldimethoxysilane, diethylenetriaminopropylmethyldiethoxysilane, and diethylenetriaminomethylmethyldiethoxysilane.

In another embodiment, the abrasive may include an abrasive modified with a cation derived from the compound of formula 2.

The cation derived from the compound of Chemical Formula 2 refers to a cation formed by binding hydrogen or a substituent to nitrogen in Chemical Formula 2. The cation may be a monovalent to trivalent cation. For example, the cation may be represented by any one of the following Chemical Formulas 2-1 to 2-7:

(In the formulas 2-1 to 2-7, X ₁ , X ₂ , X ₃ , Y ₃ , Y ₄ , Y ₅ , R ₆ , R ₇ , R ₈ , and R ₉ are each as defined in the formula 2,
R ₁₀ , R ₁₁ , and R ₁₂ each independently represent a hydrogen atom, a hydroxyl group, a substituted or unsubstituted monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

In yet another embodiment, the polishing agent may include a polishing agent modified with a salt of the compound of Chemical Formula 2. The salt of the compound of Chemical Formula 2 refers to a neutral salt of a cation and anion derived from the compound of Chemical Formula 2 described above.

The cation may be represented by any one of the above-mentioned formulas 2-1 to 2-7. The anion may be as described above for the salt portion of formula 1.

The abrasive may be included in the CMP slurry composition at 0.001% to 20% by weight, preferably 0.01% to 15% by weight, more preferably 0.05% to 10% by weight, and most preferably 0.1% to 5% by weight, 0.5% to 3% by weight. Within the above range, the insulating layer film and tungsten pattern wafer can be polished at a high polishing rate.

Compound of formula 3 or its complex compound

The compound of formula 3 may be included in a composition to form a catalyst. The catalyst may be a complex compound between the compound of formula 3 and a metal ion.

(In the above Chemical Formula 3,
R ¹ , R ² , and R ³ each independently represent a single bond or a substituted or unsubstituted alkylene group having 1 to 3 carbon atoms;
R ⁴ , R ⁵ , and R ⁶ each independently represent a substituted or unsubstituted alkylene group having 1 to 3 carbon atoms;
M ¹ , M ² and M ³ each independently represent OH or O ⁻ M ⁺ (M ⁺ is a monovalent cation).

The compound of Chemical Formula 3 has a closed ring structure having three nitrogens. In addition, the compound of Chemical Formula 3 has a total of three -C(=O)M ¹ (M ² or M ³ ) with -C(=O)M ¹ (M ² or M ³ ) connected to each nitrogen. Therefore, when the compound of Chemical Formula 3 forms a complex with a metal ion, the three -C(=O)M ¹ (M ² or M ³ ) of the compound of Chemical Formula 3 are all bonded to the metal ion, and there is no -C(=O)M ¹ (M ² or M ³ ) remaining unbonded to the metal ion, and the three nitrogens of Chemical Formula 3 are also bonded to the metal ion, thereby significantly increasing the stability of the catalyst. Through this, the composition of the present invention can increase the polishing rate of a tungsten pattern wafer and improve the flatness after polishing.

In one embodiment, in Formula 3, R ¹ , R ² , and R ³ may each independently be a substituted or unsubstituted alkylene group having 2 to 3 carbon atoms, R ⁴ , R ⁵ , and R ⁶ may each independently be a substituted or unsubstituted alkylene group having 1 to 2 carbon atoms, and M ¹ , M ² , and M ³ may each independently be OH.

In one embodiment, the monovalent cation in Formula 3 may be an alkali metal cation, such as Li ⁺ , Na ⁺ , or K ⁺ .

For example, the compound of formula 3 may be a compound of formula 3-1 below or its salt with an alkali metal cation:

The complex compound of the compound of Chemical Formula 3 may be a complex compound in which a metal ion is coordinately bonded to the compound of Chemical Formula 3. The metal ion may be an iron ion, for example, a divalent iron cation (Fe2 ⁺ ) or a trivalent iron cation (Fe3 ⁺ ). When the compound of Chemical Formula 3 forms a complex compound, the compound of Chemical Formula 3 may be bonded to the metal ion by removing H or M ⁺ from ^M1 , ^M2 , and ^M3 .

In one embodiment, an example of the complex compound of the compound of Chemical Formula 3 may be a complex compound represented by the following Chemical Formula 4: As shown in Chemical Formula 4, three nitrogen atoms and three -C(=O)M ¹ (M ² or M ³ ) are bonded to Fe:

The metal ions may be derived from a compound containing a divalent iron cation, a compound containing a trivalent iron cation, or a hydrate thereof, including, but not limited to, one or more of iron chloride (FeCl ₃ ), iron nitrate (Fe(NO ₃ ) ₃ ), iron sulfate (Fe ₂ (SO ₄ ) ₃ ), or a hydrate thereof.

The complex compound of the compound of formula 3 may be formed by a chelate bond forming reaction between the compound of formula 3 and an iron trivalent cation-containing compound or a hydrate thereof.

The compound of formula 3 or its complex may be included in the CMP slurry composition in an amount of 0.001% to 10% by weight, preferably 0.001% to 1% by weight, more preferably 0.001% to 0.5% by weight, for example, 0.001% to 0.1% by weight, 0.001% to 0.01% by weight. Within this range, the polishing speed of the tungsten film can be increased and the polishing flatness can be improved.

The CMP slurry composition may further include one or more of an oxidizer, an amino acid, and an organic acid.

The oxidizing agent can oxidize the tungsten pattern wafer and make it easier to polish the tungsten pattern wafer.

The oxidizing agent may include one or more of inorganic percompounds, organic percompounds, bromic acid or its salts, nitric acid or its salts, chloric acid or its salts, chromic acid or its salts, iodic acid or its salts, iron or its salts, copper or its salts, rare earth metal oxides, transition metal oxides, and potassium dichromate. The "percompound" is a compound that contains one or more peroxide groups (-O-O-) or an element in the highest oxidation state. Preferably, a percompound can be used as the oxidizing agent. For example, the percompound may be one or more of hydrogen peroxide, potassium periodate, calcium persulfate, and potassium ferricyanide, preferably hydrogen peroxide.

The oxidizing agent may be included in the CMP slurry composition in an amount of 0.01% to 20% by weight, preferably 0.05% to 10% by weight, and more preferably 0.1% to 5% by weight. Within this range, the polishing speed of the tungsten pattern wafer can be improved.

Amino acids can be included in CMP slurry compositions containing the above-mentioned abrasives to further increase the polishing rate of tungsten.

The amino acids may include glycine, lysine, alanine, histidine, serine, glutamine, valine, leucine, phenylalanine, arginine, aspartic acid, glutamic acid, threonine, asparagine, glutamine, cysteine, proline, etc. Preferably, the amino acids may include one or more of glycine, lysine, alanine, and histidine, more preferably glycine.

The amino acid may be included in the CMP slurry composition at 0.001% to 10% by weight, preferably 0.005% to 5% by weight, more preferably 0.01% to 1% by weight, and most preferably 0.02% to 0.5% by weight. Within this range, the polishing speed of the tungsten film can be increased.

Organic acids can increase the polishing rate of tungsten patterned wafers.

The organic acid may include an organic acid having one or more carboxyl groups, preferably an organic acid having one carboxyl group. For example, the organic acid may include one or more of acetic acid, propionic acid, butyric acid, and valeric acid.

The organic acid may be included in the CMP slurry composition at 0.001% to 10% by weight, preferably 0.002% to 5% by weight, more preferably 0.005% to 3% by weight, and most preferably 0.01% to 1% by weight. This range enhances the dispersion stability of the abrasive, and can prevent the abrasive from clumping and/or agglomerating even after a long time has passed since production.

The CMP slurry composition may have a pH of 2 to 7. The present invention uses the above-mentioned modified silica as an abrasive, thereby realizing a high polishing rate of tungsten pattern wafers even at a weakly acidic pH compared to conventional strongly acidic pH. In one embodiment, the CMP slurry composition may have a pH of 2 to 6, 3 to 6, 4 to 6, or 5 to 6.

The CMP slurry composition may further include a compound containing an iron trivalent cation or a hydrate thereof, specifically, but not limited to, one or more of iron chloride (FeCl ₃ ), iron nitrate (Fe(NO ₃ ) ₃ ), iron sulfate (Fe ₂ (SO ₄ ) ₃ ), or a hydrate thereof.

The iron trivalent cation-containing compound or its hydrate may be included in the CMP slurry composition in an amount of 0.001% to 10% by weight, preferably 0.01% to 1% by weight, and more preferably 0.1% to 0.5% by weight. Within this range, the catalyst activity stability may be improved, and the polishing performance may be maximized.

The CMP slurry composition may further include a pH adjuster to adjust the pH.

The pH adjuster may include one or more of an inorganic acid, such as nitric acid, phosphoric acid, hydrochloric acid, and sulfuric acid. The pH adjuster may include one or more of a base, such as aqueous ammonia, sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium carbonate, and potassium carbonate.

The CMP slurry composition may further include conventional additives such as biocides, surfactants, dispersants, and modifiers. The additives may be included in the composition in an amount of 0.001% to 5% by weight, preferably 0.002% to 1% by weight, and more preferably 0.005% to 0.5% by weight. In this range, the polishing rate is not affected and the effect of the additives can be realized.

The tungsten polishing method of the present invention includes a step of polishing tungsten using the CMP slurry composition for tungsten polishing of the present invention. In one embodiment, the present invention is a method for polishing a tungsten pattern wafer, which includes a step of polishing a tungsten pattern wafer using the CMP slurry composition for tungsten pattern wafer polishing of the present invention.

The configuration and operation of the present invention will be described in more detail below through preferred embodiments of the present invention. However, these are presented as preferred examples of the present invention and should not be construed as limiting the present invention in any way.

Manufacturing example 1

A compound of the following formula 5 (Momentive, EDPS) was added dropwise to colloidal silica (PL3, Fuso) with an average particle size of 70 nm in a ratio of 0.04 mol under acidic conditions and reacted at pH 3.8 and 65°C for 8 hours to produce silica modified with the compound of the following formula 5 (zeta potential: +25 mV, average particle size: 70 nm). The zeta potential was measured using a Zetasizer ZS (Malvern).

Example 1

0.5 mmol of the compound of Formula 3-1 and 0.5 mmol of iron chloride (FeCl ₃ ) were mixed and refluxed, and then reacted for 24 hours to form the complex compound of Formula 4. A composition was prepared by containing 1.2 wt % of the modified silica of Preparation Example 1 as an abrasive, 0.001 wt % of the complex compound of Formula 4, 300 ppm of acetic acid as an organic acid, and 0.16 wt % of glycine, based on the total weight of the CMP slurry composition, with the remainder being deionized water. The CMP slurry composition was prepared by adjusting the pH of the CMP slurry composition to pH 5.6 using nitric acid or aqueous ammonia as a pH adjuster.

Examples 2 and 3

A CMP slurry composition was prepared in the same manner as in Example 1, except that the content of the compound of Chemical Formula 4 in Example 1 was changed as shown in Table 1 below. In Table 1 below, "-" means that the corresponding component is not included.

Comparative Example 1

A CMP slurry composition was prepared in the same manner as in Example 1, except that 0.002 wt % of the complex compound Fe-EDTA (ethylenediaminetetraacetic acid) was used instead of the complex compound of Chemical Formula 4 in Example 1.

Comparative Example 2

A CMP slurry composition was prepared in the same manner as in Example 1, except that 0.006 wt % of the complex compound Fe-EDTA was used instead of the complex compound of Chemical Formula 4 in Example 1.

Comparative Example 3

A CMP slurry composition was prepared in the same manner as in Example 1, except that 0.002 wt % of the complex compound Fe-DTPA (diethylenetriamine pentaacetic acid) was used instead of the complex compound of Chemical Formula 4 in Example 1.

Comparative Example 4

A CMP slurry composition was prepared in the same manner as in Example 1, except that 0.006 wt % of the complex compound Fe-DTPA was used instead of the complex compound of Chemical Formula 4 in Example 1.

The CMP slurry compositions produced in the examples and comparative examples were subjected to polishing evaluation under the following polishing evaluation conditions. The results are shown in Table 1 below.

[Polishing evaluation conditions]

1. Grinding machine: Reflexion LK 300mm (AMAT)

2. Polishing conditions: Polishing pad: VP3100/Rohm and Haas Co. Head speed: 35 rpm
- Platen speed: 33 rpm
- Grinding pressure: 1.5 psi
- Retainer Ring Pressure: 8 psi
- Slurry flow rate: 250 ml/min - Polishing time: 60 seconds

3. Polishing target - Tungsten pattern wafer (MIT854, 300 mm)
- The tungsten pattern wafer was polished for 60 seconds with a Reflexion LK300mm polisher using an IC1010/SubaIV Stacked (Rodel) polishing pad at a head speed of 101 rpm, a platen speed of 100 rpm, a polishing pressure of 2.0 psi, a retainer ring pressure of 8 psi, and a mixture flow rate of 240 ml/min, using a mixture of tungsten polishing CMP slurry STARPLANAR7000 (Samsung SDI) and deionized water mixed in a weight ratio of 1:2, with hydrogen peroxide added to the mixture. Through this, the tungsten metal film layer was removed to reveal the oxide film/metal pattern.

4. Polishing speed of oxide film (unit: Å/min): After evaluation under the above polishing conditions, the difference in film thickness before and after polishing was converted using an optical interference film thickness measuring device (reflectometer) to determine the polishing speed of the oxide film.

5. Erosion (unit: Å): After evaluation under the above polishing conditions, the pattern profile was measured using an InSight CAP Compact Atomic Profiler (Bruker). Erosion was calculated based on the height difference between the peri oxide and cell oxide in the 0.18/0.18 μm pattern area of the polished wafer. The scan speed was 100 μm/sec, and the scan length was 2 mm.

6. △Erosion (unit: Å): After evaluation under the above polishing conditions, the line/space area in the 0.18/0.18 μm pattern area was scanned once in contact mode over a total of 2 mm, 1 mm to the left and right of the center, and then calculated based on the height difference between the tungsten and the cell oxide.

7. Protrusion (unit: Å): After evaluation under the above polishing conditions, a 2 μm x 2 μm pattern area was scanned to create a 3D image, and calculations were performed based on the height difference.

As shown in Table 1, the CMP slurry composition of the present invention contains an iron complex compound containing a closed ring ligand of formula 3, and thus has the effect of improving erosion while showing similar polishing speed and protrusion compared to the case where an iron complex compound containing an existing open ring ligand is used.

As shown in Table 1, when compared at the same usage content, iron complex compounds having closed ring ligands provided an erosion improvement effect with an improvement in △erosion of about 20 to 50 nm compared to iron complex compounds having open ring ligands such as Fe-EDTA or Fe-DTPA. In addition, when evaluated by content, it was found that even at low contents, the oxide film polishing speed was maintained while an erosion improvement effect was observed.

Simple variations and modifications of the present invention can be easily implemented by those having ordinary skill in the art, and all such variations and modifications are considered to be within the scope of the present invention.

Claims (12)

A CMP slurry composition for tungsten polishing, comprising at least one solvent selected from polar and non-polar solvents; an abrasive; and a compound represented by the following formula 3 or a complex compound thereof:
(In the above Chemical Formula 3,
R ¹ , R ² , and R ³ each independently represent a single bond or a substituted or unsubstituted alkylene group having 1 to 3 carbon atoms;
R ⁴ , R ⁵ , and R ⁶ each independently represent a substituted or unsubstituted alkylene group having 1 to 3 carbon atoms;
M ¹ , M ² and M ³ each independently represent OH or O ⁻ M ⁺ (M ⁺ is a monovalent cation). The CMP slurry composition for polishing tungsten pattern wafers according to claim 1, wherein the compound of formula 3 is a compound of formula 3-1 below or a salt thereof with an alkali metal cation:
. The CMP slurry composition for tungsten polishing according to claim 1, wherein the complex compound is a compound of formula 3 coordinately bonded to a metal ion. 4. The CMP slurry composition for polishing tungsten according to claim 3, wherein the metal ions are divalent iron cations (Fe2 ⁺ ) or trivalent iron cations (Fe3 ⁺ ). The CMP slurry composition for tungsten polishing according to claim 1, wherein the complex compound is a complex compound represented by the following chemical formula 4:
. The CMP slurry composition for tungsten polishing according to claim 1, wherein the compound of formula 3 or its complex compound is contained in the CMP slurry composition in an amount of 0.001% to 10% by weight. The CMP slurry composition for tungsten polishing according to claim 1, wherein the abrasive comprises at least one of an unmodified abrasive and a modified abrasive. The CMP slurry composition for tungsten polishing according to claim 7, wherein the modified abrasive contains silica modified with an aminosilane having 1 to 5 nitrogen atoms. The CMP slurry composition for tungsten polishing according to claim 1, further comprising one or more of an oxidizing agent, an amino acid, and an organic acid. The composition comprises 0.001% to 20% by weight of the abrasive, 0.001% to 10% by weight of the compound of formula 3 or its complex compound, 0.001% to 10% by weight of the organic acid, 0.001% to 10% by weight of the amino acid, and 30% to 99% by weight of the solvent. The CMP slurry composition for tungsten polishing according to claim 9. The CMP slurry composition for tungsten polishing according to claim 1, wherein the CMP slurry composition has a pH of 2 to 7. A method for polishing tungsten, comprising the step of polishing tungsten using the CMP slurry composition for tungsten polishing according to any one of claims 1 to 11.